專四情態(tài)動詞講解

1、情態(tài)動詞情態(tài)動詞 *情態(tài)動詞情態(tài)動詞: will（愿意）, shall（將）, must（必須）, can, may, would, should(應(yīng) 該), might, could, ought to, used to（過去 常常）, need（需要）, dare（竟敢）， have to（不得不） 1.表示已經(jīng)發(fā)生的情況表示已經(jīng)發(fā)生的情況 (1) must have +過去分詞，表示對已發(fā)生情況的肯定 推測，譯為“(昨 天)一定”。如： My pain must have been apparent the moment I walked into the room, for the f

2、irst man I met asked sympathetically: “Are you feeling all right?” (2) cant/couldnt have +過去分詞，表示對已發(fā)生 情況的否定推測，譯為“(昨天)一定沒”。 如： Mary couldn t have received my letter; otherwise she would have replied before now (3) may/might have +過去分詞，表示對已發(fā)生的事 情做不肯定、可能性很小的推測，或事實(shí)上根本沒 發(fā)生，譯為“也許”。如： At Florida Powers Cry

3、stal River plant, a potentially serious leakage of radioactive water may have been unknowingly caused by an electrician. 2.表示虛擬語氣表示虛擬語氣 (1) neednt have+過去分詞，表示做了不必做的事，譯為“其 實(shí)沒必要”。如： As it turned out to be a small house party, we neednt have dressed up so formally. 注意：did not need to do 動作并沒發(fā)生 例：I did

4、nt need to get up early, so I got up until 9 a.m. (2) should /should not have +過去分詞，表示應(yīng)該做某事但 實(shí)際上未做，或本不應(yīng)該做但實(shí)際上做了, 譯為“本(不)應(yīng) 該”。如： I regret having left the work unfinished; I should have planned everything ahead carefully. (3) ought to have+過去分詞，表示動作按理該發(fā)生了，但 實(shí)際上未發(fā)生，譯為“該”，與should的完成式含義 類似。如： The porter

5、ought to have called t he fire-brigade as soon as he saw the fire in the stock, which went up in smoke. (4) could have+過去分詞，表示過去本來可以做但卻未做， 譯為“完全可以”。如： What you said is right, but you could have phrased it more tactfully. (5)may/might have + 過去分詞，表示過去可以做但實(shí)際 未做，譯為“(那樣)也許會”。如： It might have been better

6、 to include more punchy statistics and photos of equipment in the introduction to further assist first-time office automation managers. 3.幾個情態(tài)動詞?？嫉木湫蛶讉€情態(tài)動詞常考的句型 (1)may/might (just) as well“不妨，最好”，與had better相近。如： Since the flight was cancelled, you might as well go by train. (2)cannot/canttoo “越越好，怎

7、么也不過分”。注意這 個句型的變體cannotover。如： You cannot be too careful when you drive a car. The final chapter covers organizational change and development. This subject cannot be overemphasized. (3)usednt或didnt use to為used to (do)的否定式。 (4)should 除了“應(yīng)該”一層意思外，大綱還規(guī)定要掌握其“竟然” 的意思。如： I didnt expect that he should have

8、 behaved like that 情態(tài)動詞一般用法的否定：情態(tài)動詞一般用法的否定： mustnt 不準(zhǔn), 禁止，不要 cant (couldnt) 不會；不能； may (might) not 不可以; neednt 沒必要 ( = dont have to ) used notusednt to或didnt use to 過 去不 dare not 不敢 *情態(tài)動詞情態(tài)動詞have過去分詞結(jié)構(gòu)表示輕微的責(zé)備和后悔過去分詞結(jié)構(gòu)表示輕微的責(zé)備和后悔 肯定：過去應(yīng)該做而沒有做； 否定：過去不該（不必）做而做了。 mightcouldhave過去分詞：“本來可以，早就應(yīng)該” （只用于肯定句，且不

9、能用（只用于肯定句，且不能用may, can） You could have told me you were going to be late!.你應(yīng) 當(dāng)早告訴我你會晚到的！ should（ought to）have過去分詞：“本應(yīng)”（沒做） should not（ought not to）have過去分詞：“本不該” （做了） You should not have handed in your composition yesterday morning.你本不應(yīng)把作文交了。 You should have been here earlier.你應(yīng)該早點(diǎn)來才對。 . 3. needntha

10、ve過去分詞：“本不必， 本不須”（need只用于否定句）（做了） You neednt have woken her up. Its only six你其實(shí)不必叫醒她?，F(xiàn)在才六點(diǎn)。 注意：注意：did not need to do 動作并沒發(fā)生動作并沒發(fā)生 （沒做）（沒做） 例：I didnt need to get up early, so I got up until 9 a.m 八大注意點(diǎn)八大注意點(diǎn) 1.在以could, might 表示征詢對方意見或表示請求時，回答應(yīng)相 應(yīng)使用can, may Might I watch TV after supper? Yes, you _. A.

11、 may B. must C. might D. can 2. May I / we ？這一類疑問句的肯定回答為Yes, please.或 Certainly；否定回答為Please dont.或No, you mustnt. 例如： “May we leave now?” “No, you mustnt. You havent finished your home work yet.” 3. need I / we ？這一類疑問句的肯定回答為Yes, we must; 否定回答為neednt 4. 在回答must引起的問題時，肯定must; 如果是否定的答復(fù)， 不能用mustnt，而要用ne

12、ednt或dont have to 5. I wish to go home with you, may I? 6. Do help yourself to have fruit, wont you/ will you? （表示一種委婉的請求） 7.Shall 用于第三人稱，表示許可，允許 8. lets do this job, shall we? Let us do this job, will you? 9. should 也表示驚訝的語氣， 例如：I was shocked that she should have said such a thing to you.(她竟然對你說那樣的

13、話,) 兩大類區(qū)別：兩大類區(qū)別： 一、表示能力: can, be able to be able to 能用于各種時態(tài)。 can / could 只能表示現(xiàn)在或過去的能力 *was / were able to : “設(shè)法做成某事” 相當(dāng)于相當(dāng)于 managed to do sth succeeded in doing sth. be able to與 can 1）cancould 表示能力；可能 (過去時用could), 只用于現(xiàn)在式和過去式(could)。be able to可以用于各種時態(tài)。 They will be able to tell you the news soon. 他很快

14、就能告訴你 消息了。 2）只用be able to a. 位于助動詞后。 b. 情態(tài)動詞后。 c. 表示過去某時刻動作時。 d. 用于句首表示條件。 e. 表示成功地做了某事時，只能用was/were able to， 不能用 could。 He was able to flee Europe before the war broke out. = He managed to flee Europe before the war broke out. can用于表示“能力”時是指現(xiàn)在的能力，過去或?qū)淼?能力通常用was/were able to或will/shall be able to表示

15、。 eg. She was able to go to school yesterday. Soon she will be able to swim a quarter of a mile. Can的過去式形式could也可用于表示泛指過去的能力。如： I could read when I was four. 但不能用于表示特定的某一過去能力，如不能說： *He could swim halfway before he got tired. He was able to swim halfway before he got tired. 上述這種用法的區(qū)別不存在于否定句中。在否定句中， c

16、ouldnt與was/were not able to 可以互換使用。 eg. I couldnt see him again before he left. I wasnt able to see him again before he left. . 注意的一點(diǎn)是：can也可以用于表示“許可”。它可以表 示現(xiàn)在許可或?qū)碓S可，過去許可用could表示，此時一 律不能用be able to的某種形式替換。 二、used to 和would 的區(qū)別 used to過去常常（但現(xiàn)在已無此習(xí)慣現(xiàn)在已無此習(xí)慣，would無此含義） He used to drink beer, now he drin

17、ks wine.他過去喝 啤酒，現(xiàn)在喝白酒。 would只能用來談動作；只能用來談動作；used to用來談動作或狀態(tài)（可用來談動作或狀態(tài)（可 與與be, live, like, stay等狀態(tài)動詞連用）：等狀態(tài)動詞連用）： He would get up early when he lived in the country.他住 在鄉(xiāng)下時總是早起。 We used to live in a small town.（不能用would） Be used to doing sth: 習(xí)慣于做某事習(xí)慣于做某事 should的用法的用法 1. (shall的過去式的過去式,表示過去將來表示過去將來)將

18、將 We hoped that we should be able to do that. 我們希望我們能這樣做。我們希望我們能這樣做。 2. (表示語氣較強(qiáng)的假設(shè)表示語氣較強(qiáng)的假設(shè))萬一萬一,竟然竟然 If the car should break down on the way, you would have to walk back. 萬一汽車中途拋錨萬一汽車中途拋錨,你就得走回來。你就得走回來。 3. (表示可能性、推測、推論或期待表示可能性、推測、推論或期待)可能可能,該該 She should be here any minute. 她該馬上就到。她該馬上就到。 Dinner sh

19、ould be ready by now. 此刻晚飯應(yīng)該做好了。此刻晚飯應(yīng)該做好了。 4. (表示義務(wù)、責(zé)任表示義務(wù)、責(zé)任)應(yīng)該應(yīng)該,應(yīng)當(dāng)應(yīng)當(dāng) You should do as she says. 你應(yīng)當(dāng)照她說的去做。你應(yīng)當(dāng)照她說的去做。 He should work harder. 他應(yīng)該更加努力。他應(yīng)該更加努力。 You should help your mother with the housework. 你應(yīng)該幫你母親做家務(wù)。你應(yīng)該幫你母親做家務(wù)。 5. (表示委婉、謙遜表示委婉、謙遜)可可,倒倒 6. (表示感情、意志等表示感情、意志等)竟然會竟然會; 應(yīng)該應(yīng)該 Im sorry i

20、t should be this way. 很遺憾很遺憾,事情竟會是這個樣子。事情竟會是這個樣子。 Its strange that he should be absent. 真奇怪，他竟會缺席。真奇怪，他竟會缺席。 You shouldnt have told him about it. 你不該把這件事告訴他的。你不該把這件事告訴他的。 7. (表示建議、命令、決定等表示建議、命令、決定等)應(yīng)該應(yīng)該,必須必須 Crime should be punished. 犯罪應(yīng)受懲罰。犯罪應(yīng)受懲罰。 8. (表示目的表示目的)會會,可以可以 He stood away so that we shoul

21、d enter the room first. 他讓開一步他讓開一步,讓我們先進(jìn)屋。讓我們先進(jìn)屋。 9. (表示結(jié)果、意愿等表示結(jié)果、意愿等)就就,該該 10. (表示征求同意等表示征求同意等)可以可以,該該 Who should I see about my schedule 1.You _ Jim anything about it. It was none 1.You _ Jim anything about it. It was none of his business. of his business. （20042004） A. neednt have told B. neednt

22、 tell A. neednt have told B. neednt tell C. mustnt have told D. mustnt tellC. mustnt have told D. mustnt tell A，neednt have done表示本不必做而做了。沒 有mustnt have done的形式，但可以說cant have done，表示不大可能。 2.He _ the 8:20 bus because he didnt 2.He _ the 8:20 bus because he didnt leave home till 8:25. leave home till

23、8:25. （19941994） A. couldnt have caught B. ought to have A. couldnt have caught B. ought to have caughtcaught C. shouldnt have caught D. must not have C. shouldnt have caught D. must not have caughtcaught A，couldnt have done表示不可能做了某事 3.He _ unwisely3.He _ unwisely， but he was at least but he was at

24、least trying to do something helpful. trying to do something helpful. （19991999） A. may have acted B. must have acted A. may have acted B. must have acted C. should act D. would actC. should act D. would act A. may have done表示過去可能做過某事，表示過去可能做過某事，B表表 示一定做過，推測的可能性很大示一定做過，推測的可能性很大 4.Loudspeakers were f

25、ixed in the hall so that everyone _an opportunity to hear the speech. （06） A. ought to have B. must have C. may have D. should have D. So that 引導(dǎo)的目的狀語從句，與情態(tài)動詞的搭 配有：so that +主語+may, might, shall, should等。 因?yàn)橹髡Z用過去時，所以D選項(xiàng)符合題意 6.“You _borrow my notes provided you take care of them, ”I told my friend. (0

26、7) A. could B. should C. must D. can D. Provided (that)+從句表示一種假設(shè)條件，provided 相當(dāng)于if。根據(jù)情況可使用虛擬語氣或陳述語氣，這里 表示真實(shí)的條件句。英語中表示”許可，建議“，在口 語中常用can/may,而不用could/might.這里正是口語中 的給與”許可“的意思。故D正確。 7.She_fifty or so when I first met her at the conference. （07） A. must be B. had been C. could be D. must have been D.英語中表示”肯定“的推測，用情態(tài)動詞must。如果是 對現(xiàn)在的推測，用must do;對過去的推測，是must have done